House heating system



July 19, l932. H. DOHERTY HOUSE HEATING SYSTEM Original Filed Jan. 22,1925 2 Sheets-Sheet 1 Svwemtoz HENRY L, DOHERTY m WW July 19, 1932. H.L. DOHERTY 1,868,051

HOUSE HEATING SYSTEM Originai Filed Jan. 22, 1925 2 Sheets-Sheet 2vwewtoz HE/VR) L. DOHERTY 351 /1/5 flttol/WJ Patented July 19, 1932UNITED STATES PATENT OFFICE HENRY L. DOHERTY, OF NEW YORK, N. Y.,ASSIGNOR TO COMBUSTION UTILITIES COR- PORATION, OF NEW YORK, N Y., ACORPORATION OF MAINE HOUSE HEATING SYSTEM Original application filedJanuary 22, 1925,- Serial 110. 3,907. Divided and this application filedKay 29,

1928. Serial The present invention relates to fluid fuel heatingsystems. More particularly the invention relates to domestic furnaceburners and combustion controlling apparatus. This inventionwasoriginally described in my application Serial No. 3,907, filed Jan.22, 1925, of which this is a division. This original application hasmatured into U. S. Patent No. 1,819,459, dated August 18, 1931.

It'has been proposed to operate systems for heating houses, raisingsteam, and like purposes, automatically, the fire under the boiler beingcontrolled automatically by a thermostat or by means responsive to thepressure in the boiler, or in other ways in order that the furnace, orfurnace and boiler, should require a minimum of attention. Certain ofthe automatic systems just referred to burn gas, oil, or coal, but themajority of the features of the present invention have to do with theuse of gas or oilseparate'ly and jointly.

.The automatic gas heating systems have been handicapped by the highcost of furnishing gas for domestic heating. Such a. system must bedesigned to furnish enough heat for the coldest days of the year. Thegas company must therefore provide equipment including gas generatingplant and auxiliaries as well as distributing mains, regulators, metersand the like, for supplying the large occasional demand for heating gasand then permit the equipment forthis purpose to be idle most of thetime. Therefore if the gas for house heating and the like is charged itsproper part of the fixed charges incurred in its manufacture, the costof heating entirely by gas becomes too high to be considered except bythose having unusually large incomes.

On the other hand, the domestic oil burning systems have been limited tothe use of a relatively high priced quality of oil. Also, they oftengive off an unpleasant odor. Moreover, both the gas systems and the oilsystems have been relatively expensive to operate and complicated inconstruction as compared with coal burning systems.

One object of the invention is to provide apparatus for burning fuel ina domestic furnace by which a relatively expensive and readilyinflammable fuel such as gas is used for the normal load heatingpurposes of the furnace with the supply of gas being limited to a fixedamount and when the demand for more heat is required than will beprovided by the fixed amount of gas, it will. be supplemented by arelatively cheap and not easily ilflarlnmable fuel such as the cheapergrades o 01 A second object of the present invention is to improve theperformance of automatic house heating systems and steam raising systemsfrom the standpoint of the householder, or person in charge of theapparatus.

A third object of the present invention is to provide a combined gas andoil burning system having high eificiency and reliability.

Another object of the present invention is to provide an odorlessapparatus for burning oil in domestic heating systems.

A further object of the present invention is to provide apparatuscapable of satisfactorily burning heavier, and therefore cheaper oil,than is now commonly used in automatic house heating systems.

The novel features of the present invention are pointed out withparticularity'in the appended claims.

The invention, together with further objects and advantages, will bestbe understood from the following description taken in connection withthe accompanying drawings, in which Fig. 1 is a view of an apparatusadapted to operate in accordance with the present invention the viewbeing partly diagrammatic, parts shown in section, and parts inelevation for purposes of illustration.

Fig. 2 is an elevation on a larger scale of the gas burner and gascontrolling portion of the apparatus illustrated in Fig. 1, parts beingshown in sect-ion.

Fig. 3 is a plan of a portion of the gas' burner illustrated in Fig. 2.

Fig. 4 is avertical, central section of the oil drawback deviceillustrated in Fig. 1.-

Fig. 5 is a plan of the oil burner illustrated in Fig. 1.

Fig. 6 is a section of the oil burner taken refractory material. '40

on the line 66 of Fig. 5, looking in the dimetal plate 16 placed in thelower portion ofthe furnace 12 and resting on the lugs 18 ordinarilyused to support the grates. The sheet 16 is centrally apertured toreceive the burner apparatus 14 which projects u into the lower portionof the furnace 12. pparatus 14 is mounted at one end of a flue or airbox 20 which extends into the ash pit 22 of the furnace 12 through theordinary doorway for removing the ashes.

- The burner apparatus 14 comprises a gas burner 26 and an oil burner28, burner 26 being of annular or ringlike form having a central openingthrough which burner 28 projects. Gas burner 26, Figs. 2 and 4, includesa considerable number of individual burner tips 30, 30 extending in aring around its upper edge and has also a number of tips 32, 32,adjacent the upwardly projecting tips 30, but inclined inwardly somewhattoward the center of the burner 26, so that flames from the tips 32 liein position to strike the edge of and be drawn into a stream of atomizedoil issuing from the centrally positioned oil burner 28. Surrounding thetips 30 and 32 and extending upwardly above the level of the same is ahell or cylinder 34. Bell 34 may be of cast iron or of fire brick orlike refractory material, or it may be cast iron lined with Resting onthe upper edge of cylinder 34 is a spider 36 supporting a central plateor button 38, which is made of cast iron, or fireclay, and so positionedas to contact with and spread oil flame issuing from the oil burner 28and insure the thorough mingling of the oil and oil flame from burner 28with the gas and gas flame from burner 26. The upper edge of cylinder34, moreover, is notched as illustrated at 39, Fig. 1, so that flamefrom burners 26 and 28 may spread and issue from the cylinder 34somewhat laterally as well as upwardly.

It is well known that not all types of boilers are equally as eflicientwhen fired by gas.

When the amount of hot gases passing through the boiler is small ascompared to the size of the passages of the'boiler, the efficiency oftensuffers unless the heating surfaces receive heat by radiation. Theapparatus according to the present invention is "therefore designed sothat the flame produced in the firebox when using gas only may be madeeither luminous or non-luminous as required in order to obtain bestefficiency with the particular type of boiler with which a given burnerapparatus is to be used. Ac-

siderable percentage of their heating surface in position to receiveradiation from a coal fire on the grate. Moreover, when the systemaccording to the present invention is applied to a domestic type boiler,the space designed to be occupied by coal and ashes is available toreceive heat by radiation from burner 26. It will be clear from thedrawing that the active surface of the boiler is notreduced according tothe present invention by refractory material placed against it topromote the combustion of the oil. Therefore, when the apparatus isadjusted to give a luminous "flame, the flame issuing from cylinder 34radiates directly to all parts of the boiler surface which would receivedirect heat or radiation from a coal fire. As it is good practice toburn fuel oil with a luminous flame, no attempt is made to provide meansfor ad usting the apparatus to a non-luminous flame when the oil isbeing burned.

According to the present invention, moreover, the cylinder 34 has a ringof apertures 40, 40 therein at a level slightly above the ends of theburner tips 30 whereby products of combustion may be drawn into theflame within the cylinder 34 to lengthen the flame and assist inimproving eflicient combustion of theioil.

Great difficulty has been experienced heretofore in using fuel oil fordomestic boiler furnaces because the amount of oil burned iscomparatively small, the fuel often has a very high viscosity, and-isquite dirty. Accordingly, the oil does not feed uniformly to the burnersand there is not sufficient combustion to maintain sufficiently hightemperatures for proper combustion. In accordance with the presentinvention an ideal condition for burn-- ing heavy fuel oils is providedby burning gas within a refractory chamber to maintain a radiatingsurface which will readily ignite fuel oil. To this end the gas is usedas the normal load fuel and is burned within the cylinder 34 inmaintaining normal heat requirements of the boiler. When the requirementof heat from the boiler increases above normal, the oil 'is introducedthrough the burner 28. At this time the gas is burning at its maximumamount. Therefore the oil is introduced into a heated chamber and into aburning gas flame. When the combined combustion of the oil andgas hassupplied the heat requirements of the boiler the oil will be cut ofifrom the burner 28 before the gas is turned down in the burner 26, andaccordingly the amount of oil being burned is sub? stantially uniformand is in suflicient amount to maintain an efiicient and ideally burningluminous oil flame. 4

The means for supplying gas and air to burner 26 and for regulating aflow of the in fine by a bracket 52. The device 50 has a mixing chamber54 which opens into the flue 20 by way of passage 56 and which connectswith the gas chamber 48 by an aperture or passage 58. The gas flowingthrough aperture 58 draws air through passage 56 and the air and gasafter mixing in chamber 54 pass through the pipe 60 within flue 20 tothe gas burner 26. In order that the flame of the burner 26 may beregulated as desired, a

needle valve 62 is arranged to govern the passage 58, valve 62 beingprojected as a pin or like form backwards through the wall of chamber 48opposite passage 58 and being slidably mounted in the wall of thechamber 48. The outer end of the valve 62 is fixed to a cap 64 slidablymounted on pins 66,66 fixed in lugs 68 on the exterior of the device50..

The cap 64 when moved up against the end of the device covers the airpassage 56 and shuts off thefiow of air to the mixing chamber 54. At thesame time cap 64 carries the valve 62 into such-a position that itcloses the gas aperture 58. Therefore by moving the capv 64 in onedirection or the other on pins 66, the flow of air and gas to the burner26 may be regulated as desired and "the cap 64 is so arranged withrespect to the valve 62 and the intake end of the air passage 56 that adesired percentage mixture of gas and air is maintained in the pipe andburner 26. The air admitted to mixing chamber 54 through passage 56 isprimary air in accordance with the ordinary nomenclature of the art. A

damper 70 is arranged to control the ad.- mission of air into the flue20 through opening 71, damper 70 bein operated through link 72 connectedto a bell lever 74 which operates the cap 64 andneedle valve 62, belllever *?4 being pivoted to a bracket 76 fixed to the part 52. One end ofbell lever 74 is connected to rod 78 and automatic means is provided foroperating the rod 7 8 in accordance with the need for heat to bedelivered by the system of which the burner apparatus P 14 is a part.

If the burner apparatus is part of a house heating system, the automaticmeans just mentioned includes a thermostat 80 placed in the room whosetemperature it is desired to control. Thermostat 80 includes two fixedcontacts 82 and 84, respectively. It also includes a movable contact arm86, the position of which is controlled by the temperature of the roomon account of the expansion and contraction of the curved metal portion88. 90 is an electric motor supplied by current through wires 92 fromthe power line 94. The circuit of motor 90 is extended through wires 96,98 and 100 to thermostat 80, wire 96 being normally connected to fixedcontact 82, wire 98 being normally connected to the arm 86 and wire 100being normally connected to fixed contact 84. Wire 100 is also connectedto an automatic thermbstat or circuit closing device 102 by means of abranch 101 while wire 98 is interrupted at point 104 and connected tothe arm 86 through the loop 99 running through the device 102.

The parts of the flue controlling devices are illustrated in Fig. 1 inthe position assumed by them when the burner 28 is inactive. The roomwhose temperature is controlled by thermostat 80 will therefore becooling off. a Assuming that the temperature of the room has declined tothe lower limit desired, the arm 86 of the thermostat 80 strikes'thecontact 82. The motor 90 is so constructed that each time its circuit isclosed, it turns its driving shaft 180 degrees and then stops. havingbeen closed as just mentioned, the motor thereupon rotates its shaft 180degrees from the position illustratedin Fig. 1. The motor 90 andthermostat control therefore just described are similar to those used inthe known Honeywell house heating system and form no part of the presentinvention. The details of motor 90 are therefore neither disclosed norclaimed herein.

' The crank or arm 106'fixed to the shaft of motor 90 is thrown down bythe movement of theomotor just mentioned and the spring 108 placed intension. Spring 108 connects the arm 106 with cord 110, cord 110 runningover pulleys 112, 112 and connecting to a cross head 114 carrying therod 78, previously mentioned. The downward pull on the spring 108 tendsto lift the cross head 114 by virtue of the pulleys 112 and thereby openthe gas valve 62 and passage 56 to bring up the gas flame of burner 26.When, however, the temperature of the room is at the upper desiredlimit, arm 86 of the thermostat 80 strikes the fixed contact 84 againclosing the circuit of motor 90 and causing said motor shaft to executeanother half The circuit of motor 90' turn or rotary movement of The arm.Fig. 1, the tension of spring 108 being re laxed and the arm 78permitted to drop to close off the flow of gas to burner 26.

However, according to the present invention it is preferred that the gasflame be increased gradually and turned off gradually, and for thispurpose a retarding means is connected to the cross head 114, saidretard-' ing means comprising a rod 116 fixed to cross head 114 andextending into the dash pot cylinder 118. Within the dash pot 118, rod116 is connected to a weighted piston 120, (Fig. 2), the dash pot 118being filled with light oil, preferably a mixture of kerosene and lightlubricating oil, and the ends of the dash pot above and below the piston120 connected by pipe 122 (Fig. 1), having a retarding valve 124therein. When the spring 108 has been tensioned by the motor 90 as abovedescribed, the tension of the spring is resisted by the weight of piston120 and the motion of the piston is moreover retarded by the oil in thedash potso that the cross head 114 carrying the operating rod 78 canrise only gradually and the fuel to burner 26 is turned on gradually.Similarly, when the motor 90 is turned into the position illustrated inFig. 1 so that the spring 108 is relaxed, the weighted piston 120gradually carries the rod 78 downwardly and the 'movementof' rod 78correspondingly shuts ofl the flow of as to burner 26, the movement ofthe piston being resisted by oil flowing through the valve 124. It willbe seen that the parts of the gas controlling apparatus just describedare illustrated in Fig. 1 in the position assumed by them shortly afterthe motor 94 has turned the arm 106 to the uppermost position, therebyrelaxing spring 108.

The means for supplying oil to burner 28 and forstarting and stopping,the flow of the same according to the present invention will now bedescribed. The movable cross head 114 carries an insulated contact 126.A co-operating contact 128 is mounted on and insulated from the fixedstandard 130, the latter mounted on dash pot cylinder 118. Contact 126strikes contact 128 at the upper limit of travel of cross-head 114 as itmoves upward under the influence of spring 108 as previously described.Also, the contacts 126 and 128 separate as soon as cross head 114 startsdownwardly when the tension 011 spring 108,has been relaxed. Contacts126 and 128 are inserted'in the circuit of motor 1 132 which drives apump 134 furnishing oil to oil burner '28. The circuit of motor 132 istaken 011' the power line or circuit 94 through lead 136, passingthroughcontacts 126 and 128 to' the casing of motor 90 and thencethrough lead 137 to= an emergency circuit opening device 140 and thenceby lead 142 to the casing of motor 132 itself from which it returns tothe other side of power circuit 94 by lead 144. From the foregoing, itwill be seen that the oil pump from that of oil pump motor 132 and theshafts of the motor and pump are directly coupled in alinement. Alsointermediate oil pump 134 and motor 132 is an air pump- 136 furnishingair for atomizing oil from pump 134 in burner 28. The casing of air pump136 is fixed to the casings of motor 132 and pump 134 and its shaft isin alinement with those of the motor and oil pump, motor 132 and pumps134 and 136 forming a unitary structure. Oil flows to pump 134 throughpipe 138 and is forced to burner 28 through pipe 145. Air pump 136delivers air for atomi-zing the oil through pipe 24 previouslymentioned, pipe 24 running between pump 136 and burner 28.

\Vhen pump 134 has been operating to force oil to burner 28 and is thenshut down by one of the automatic controls previously described, unlessmeans were provided to prevent it, oil would stand in the upper part ofthe burner 28 when not operating. As the upper part of burner 28 issurrounded by a ring of gas jets from burner tips 30 and 32, oil sostanding in burner 28 would be carbonized by the heat of flames andwould soon clog burner28. To prevent carbonizing of oil in burner 28 adraw-back device 146 is provided in pipe 145 intermediate pump 134 andburner 28. Device 146, details of which are set out below, actsautomatically to cut 011 pump 134 from burner drops upon shutting downof pump 134 and device 146 then acts to suck back into its own casingsome of the oil in pipe 145, so that the oil in'burner 28 is drawn downbelow the level at' which it can be carbonized by heat from burner 26. A

The two devices, 102 and 140, at the burners and on the boilers,respectively, previously mentioned as formingpart of the systemaccording to the present invention operate only under abnormalconditions. Thermostat device 102 comes into operation upon theextinction of pilot light 46. When the thermostat in device 102 i smaintained at normal temperature by the heat from pilot light 46contacts are made to connect the two halves of loop 99 so that wire 98acts as a continuous wire leading to thermostat arm 86 as previouslydescribed. When,

however, device 102 cools below a certain temperature it connects wire101 with the part of loop 99 running to point 104. The action of device102 when it cools down therefore is the same as that of thermostat 80when the thermostat is heated up and upon the connection of wire 10-1with point 104 by device 102, motor if not already in that positionturns arm 106 to point upward, thereby first cutting off the oil, if thepump is'in operation and then gradually cutting 013' the gas.

Device 140 controls only the oil-pump motor 132. When the temperature orpressure within the boiler 10 exceeds certain desired limits, device 140disconnects wire 142 from wire 137, thereby interrupting the circuit ofmotor 132 and shutting down this motor and oil-pump 134. The oil toburner 28 is thereby shut off.

Secondary air as well as primary air for the gas flame is furnishedthrough opening 71, as reviously mentioned. However, damper 0 governingopening 71 is opened substantially as far as the apparatus can do sobefore the oil pump 134 is started, a very small movement of contacts126 and 128 one way or the other being suficient to start or stopoil-pump motor 132. The damper 70 is adjusted to give the proper supplyof air for the maximum flow of gas to burner 26, while primary air foroil burner 28 is supplied through pipe 24, so that it is clear anadditional supply of air is needed to furnish secondary air to burner 14when oil as well as gas is being burned. For the purpose just mentionedthere is provided a second air inlet aperture 310 in air duct 20,aperture 310 being closed by damper 312 except when oil is being burned.Damper 312 is illustrated as hinged at 314 to the outside of the topsurface of duct 20 whereby this damper closes by its own weight. Ofcourse, if the damper 312 were so placed that it did not close by itsown weight some means would need to be provided to hold it normallyclosed. In order to open damper 312 when needed, a link 316 is connectedto the unhinged end of the damper, link 316 being pivoted in turn to armor lever 318. Lever 318 is pivoted at the end removed from link 316 to afixed standard 320. Lever 318 lies above and is connected to a flexibleoperatingdiaphragm 322, diaphragm 322 being attached so as to close theupper end of cylinder 324 which is mounted on the duct, 20. A pipe 328connects the interior of air pipe 24 with the interior of cylinder 324beneath diaphragm 322. With this arrangement the same air pressure ismaintained in the cylinder 324 which exists in the pipe 24. Thereforewhen the air pump 136 is put into operation the diaphragm 322 will beactuated to open the damper 310 to admit secondary air. I

At the instant the motor 132, pumps 134 and 136 have been shut ofi bythe automatic controls, the burner 28 is still full of oil and, beingsurrounded by a ring of gas flame, oil in the upper part of burner 28would soon carbonize and prevent the operation of the burner when theoil is next pumped into it.

To prevent the carbonizing of the oil in burn- .145; and passes into achamber 330, the top of which is formed by an internal horizontal web332. The air for burner 28 is pumped thereinto from the pump 136 throughthe pipe 24, pipe 24 connecting with the burner through threaded ofiset334 connecting with the air chamber 336 lying within the burner 28 abovethe web 332. From the chamber 336 the air is conducted upwardly througha nipple 338 leading out of the chamber 336 into a burner cap 340. Apipe 342 extends through the web 332 and runs centrally through chamber336 and nipple 338 to conduct oil to within the burner cap 340. At theupper end of pipe 342 is a nozzle 344 co-operating with the cap 340 andproducing oil flame. Cap 340 has a central upwardly tapering opening 346therein and the upper end of nozzle 344 tapers upwardly on the lineparallel to the taper of the aperture 346 and projects within thisaperture, but nozzle 344 is spaced from the cap 340 so that air may passup around the nozzle through the aperture 346. Nozzle 344 has a centralaperture 348 leading upwardly and delivering oil "within the aperture346 so that air and oil are thoroughly commingled in passing through theupper portion of aperture 346. In order to further atomize the oilandthoroughly mix it with the air, the upper end of the opening 348 in theoil nozzle 344 is enlarged and cap 340 has also a series of air jetapertures 350 arranged around the centhe centre of cap 340 so that theair jets from the apertures 350 produce a swirling action of the flame.

The operation of the apparatus disclosed herein will be obvious to thoseskilled in the art from the foregoing description. For convenience ofreference however the opera tion of the apparatus according to thepresent invention will be summarized as follows:

' The fuel burning and combustion regulating apparatus of the presentinvention is applied specifically to a domestic heating furnace of thetype usually employed for burning coal. The burners and the controllingapparatus are preferably built up in a unit construction and locatedimmediately adjacent the furnace. The automatic control for the burnersand the regulating apparatus consists of a thermostat which should beplaced in a room of the house whereby the temperature of this room willbe used for controlling the heating of the house. If the room in whichthe thermostat is located has the nor-- mal temperature desired, say,for example, 70 F., the burners will be turned off and nothing but thepilot burner 4.6 willbe burning. At the time the temperature falls below70 the thermostat 80 will operate to close the power circuit in themotor 90 and at this timethe dash pot mechanism 118 will be operated bythe motor to adjust the needle valve 62 .and air valve 64 so that thegas will be introduced into the mixing pipe 60 and flow to the gasburner 26. The dash pot mechanism is so arranged that the gas will begradually increased until a predetermined maximum or fixed demand of gashas been reached. When the maximum has been reached electric contacts126 and 128 mounted on the dash pot mechanism will be made and the airand oil pump motor 132 will be set in operation to supply oil and, airto the oil burner 28. By the time the gas burner has gradually increasedthe amountof gas burned to its maximum, the refractory chambersurrounding the gas burner will be highly heated and therefore when theoil is in: troduced into the burner 28, it will be atomized into the gasflame from the burner 26 and into the heated refractory chamber 34. Atthe time the motor 132 is set into opera-- tion the oil will be suppliedto the regulating mechanism 146 in a fixed amount, and the amount of oilflowing to the burner will be uniform as long as the oil burnercontinues to operate. The oil is supplied to the burner' 28 in ameasured quantity, the measuring being accomplished by the pump 134, sothat the oil flows through a comparatively large pipe to a burner havinga comparatively large discharge orifice. When the gas is turned on bythe motor 90 the air valve in the duct 20 is gradually opened as thesupply of gas increases. This furnishes the primary and secondary airfor the gas flame. When the oil is turned on primary air is introducedby the pump 136 and the secondary air is introduced into the duct 20through the damper 310 by the regulating diaphragm 322 which is operatedby the air pressure used in the oil burner.

While the oil is burning the gas isburning at its maximum'demand and theoil burns at the predetermined fixed quantity which is normally usedwhen burning oil. These two combined fuels then continue to burn untilthe heat supplied by the boiler is sufiicient to raise the temperature"in the room of the house in which the thermostat is situated to normaltemperature. Then thermostat 80 will make such an electrical contactthat the motor 90 will be operated to set the dash pot mechanism in aposition for turning off the oil and gas. Immediately upon the operationof the motor for turning off the oil and gas the electrical contact forcontrolling the circuit of the oil and air pump will be broken, and themotor will stop. As soon as the oil pressure in the feed line and theair pressure in the air line have been decreased the suckback device 146will act to draw back the oil from the burner 28 and the damper 310 willbe closed. The gas however will not be cut off immediately, but thesupply of gas will be gradually reduced by the dash pot until it will beentirely out off unless in the meantime the room temperature has fallenso that the thermostat 80 will be operated to actuate the motor foragain turning on the gas. In this way the gas is used as the normal loadfuel to be gradually increased and decreased as the heat demandsrequire. When however the temperature in the house is such as to requiremore heat than can be supplied by the burning of the gas alone, then theoil will be turned on to supplement the gasin supplying the heatdemands. The temperature and pressure controlling device 140 is used toprevent the development of an excess temperature in a water boiler or anexcess steam pressure in a steam boiler whereby the burning of fuel maybe checked rather that injuring the boiler. The safety device 102 whichis connected with the pilot flame is arranged to operate at the time thepilot flame is extinguished in order to cut off both the oil and gas toprevent them from being supplied to the furnace when the fuel is notignited or burning.

It will be seen that the present invention provides a heat systemparticularly adapted although not limited to household heating purposesin that it is fully automatic, but

safe and rugged in operation. Moreover, the system operating accordingto the present invention burns fuel oil without odor and with. littlenoise. While the foregoing disclosure is specific in character theappended claims are not to be construed as limited to details of saiddisclosure except as to details positively included in the claims.

Having described my invention, I claim:

1. A combined. oil and gas burner comprising a refractory cylinder, anatmospheric type gas burner adapted to form a ring of gas flame withinsaid cylinder, and an oil burner arranged to project atomized oil withinsaid ring of gas flame.

2. A combined oil and gas burner comprising a refractory cylinder havingapertures in its lower portion, an atmospheric type gas burner adaptedto form a ring of gas flame within said cylinder, and an oil burnerarranged to project atomized oil within said ring of gas flame.

3. A combined oil and gas burner comprising an oil burner, a gasburner'surrounding said oil burner, a refractory cylinder surroundingand extending above said gas burner, and a refractory spreader supportedabove said oil burner.

4. A combination oil and gas burner including an annular gas burnerhaving a ring of orifices in its combustion face, and an oil burnerhaving an atomizing nozzle located centrally of the gas burnerycertainof the gas burner orifices being inclined inwardly toward a point infront of the oil burner nozzle.

5. A combination oil and gas burner including an annular gas burner, aring of orifices in the combustion face of the gas burner, certain ofsaid orifices being inclined inwardly, an oil burner located centrallywith respect to the gas burner orifices, a conduit for supplying air toburn the fuel, and means controlling the admission of air to saidconduit. v

6. A combination oil and gas burner including an annular gas burner, aring of orifices in the combustion face of the gas burner,

a portion but not all of said orifices being inclined inwardly, and anoil burner located centrally of the gas burner.

7. In combination with a furnace combustion chamber having an openingtherein, means for delivering an atomized jet of fluid fuel and air witha whirling motion to said opening, and an annular burner arranged todirect a flame across the path of said et from all sides thereof at anangle to the axis of rotation of the jet.

8. In combination with a furnace combustion chamber having an openingtherein, a gas burner adapted to project a ring' of gas flame withinsaid chamber, an oil burner arranged to project an atomized jet of oiland air within the ring of flame from said gas burner, a draft conduitextending from said opening'to a point at one side of the furnace, andmeans for adjusting the supply of air to said chamber in accordance withthe fuel supply.

In testimony whereof I aifix my signature.

HENRY L. DOHERTY.

